Wet avalanches join the long list of climate change consequences

By Kendall Brunette

You’ve planned, prepared and trained for this day.

Your legs are full of energy and ready to carry you to the summit.

You noticed the air becoming lighter with each step, but the adrenaline pushes you up the mountain with determination and perseverance.

Standing atop the summit, you look down at the white mountainside below you, anxiously and meticulously picking your line of descent.

You point your tips and send it!

Before you lies nothing but untouched powder waiting for you to carve the majestic turns most people only dream about.

With each turn you feel the freedom and exhilaration you’ve been craving.

Until…WHUMPH!

The sound every backcountry skiier or snowboarder fears – the sound of an avalanche breaking lose beneath you.

This sound has become more familiar and common in the backcountry because of climate change.  According to the U.S. Forest Service, wet avalanches are caused by rain, prolonged exposure to sun and warm temperatures.  These type of avalanches differ from the more prevalent dry avalanches, which are caused by wind-loaded snow drifts placing excess stress on the snowpack.  Climate change-induced warming trends facilitate the conversion of snow precipitation into rain at lower elevations, adding more moisture to the low-elevation snowpacks.


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Jeff Deems, research scientist at the University of Colorado Boulder’s National Snow & Ice Data Center, studies snow hydrology – the study of how snow moves and forms.

“Low-elevation snowpacks exhibit climate change impacts first,” Deems said.  “We are losing those low-elevation snowpacks – they are not accumulating as early, and they are melting faster and earlier.”

According to Deems, minimally warmer atmospheric temperatures turn a substantial fraction of snowfall episodes into rainfall events.

“At low elevations, we are seeing a diminished snow pack, either from the snow not accumulating in the first place because it rained instead, or from additional rain falling on top of the snowpack, which helps melt the snow faster,” Deems said.

Rain falling on top of the snowpack may indeed melt the snow faster, but it also increases the risk of wet avalanches.  Snow carried down mountainsides by wet avalanches tends to be heavier and concrete-like, as they are laden with excess moisture.  Wet avalanches move significantly slower than dry avalanches, which some claim to be a benefit, as it allows more time for people to escape the sliding snow.  The U.S. Forest Service says that wet avalanches are also more difficult for humans to trigger because of the differences in weight and moisture content of the snow.

According to the Colorado Avalanche Information Center, Colorado endured 223 avalanche accidents over the past four years.  Of these incidents, 33 were fatal.  Skiiers are the most common avalanche victims throughout the state, but snowboarders, snowmobilers, snowshoers and hikers are also included in the statistics compiled by CAIC.  Nationwide, snowmobilers comprise the greatest number of avalanche fatalities over the past nine years.

US av fatalities by season

Based on data from CAIC, avalanche fatalities follow a growing trend.  Over the last 60 years, the number of fatalities has steadily increased each year.  One explanation for this trend is advances in technology, leading to greater backcountry access.  Today’s snowmobiles harness greater horsepower and are specifically designed for climbing mountains in the backcountry.  Skiiers and snowboarders have gained greater backcountry access with helicopters and snowcats – fully tracked vehicles designed for on-snow travel.

Climate change is the other explanation for the increase in avalanche fatalities.  Warmer atmospheric temperatures, paired with rainfall on snowpack creates a ripe recipe for wet avalanches and the chill-inducing WHUMPH!

Deems simply says, “We know that if you change the atmosphere, you change the snowpack.”

And when you change the snowpack, you run the risk of erasing those beautifully carved turns with massively destructive wet avalanches…WHUMPH!

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